Twitter also had to move away from Ruby into a service-oriented architecture back in the late 00s. It's not a very scalable language, even when you hire people who work on the compiler.
1. Note that this is a news aggregator for tech startups. Tech startups in large cities tend to hire most of their experienced engineers from FAANG companies. So, it's in a tech startup's interest to critique FAANGs.
2. You could want to be a great startup founder or early engineer as an ambition. Probabilistically, your most straightforward path to this goal is to go to a FAANG next. Golden handcuffs, most people come in with this ambition then don't leave because there's so many pleasant aspects. Think about point #1 again.
3. If you are trying to get into a more respected tech community and are limited by visa issues, which companies tend to solve more often than individuals, it's probably in your interest to find a company [1] that will clear this hurtle for you and [2] that has a brand you can leverage. FAANG is a subset of companies that would provide that option.